Dernière mise à jour : 22-11-2017

6 sujets INAC/SPINTEC

• Electronics and microelectronics - Optoelectronics

• Solid state physics, surfaces and interfaces

 

System-level simulation and exploration flow for non-volatile neuromorphic architectures

SL-DRF-18-0278

Research field : Electronics and microelectronics - Optoelectronics
Location :

Spintronique et technologie des composants (SPINTEC)

Laboratoire Spintec (SPINTEC)

Grenoble

Contact :

François DUHEM

Benoît MIRAMOND

Starting date : 01-10-2018

Contact :

François DUHEM

CEA - DRF/INAC/SPINTEC/SPINTEC

04 38 78 52 98

Thesis supervisor :

Benoît MIRAMOND

Université Nice Sophia Antipolis - LEAT (Laboratoire d'Electronique, Antennes et Télécommunications) UMR CNRS 7248

04.92.94.28.84

Laboratory link : http://www.spintec.fr/

Hardware neural network implementation is a hot topic in research and is now considered as strategic for several international companies. Leading projects in neuromorphic engineering have led to powerful brain-inspired chips such as SyNAPSE, TrueNorth and SpiNNaker. Most of these technologies work well in centralized computing farms but will not fit embedded systems or Internet-of-Things (IoT) requirements, due to their energy consumption. Heterogeneous integration between CMOS and emergent technologies is seen as an opportunity to go past this limitation. In particular, Magnetoresistive Random-Access Memory (MRAM) is considered one of the most promising Non-Volatile Memory (NVM) technology expected to mitigate energy consumption when integrated in computing architectures. However, we still miss a high-level perspective on how NVM actually benefits energy efficiency and how it can be improved any further.

In this context, the aim of the thesis is to enable exploration of NVM-based neuromorphic accelerators by defining a framework for the joint, high-level modelling of digital logic and NVM-based functions. The framework will enable exploration of new architectural choices based on NVM properties to understand how they affect the performance/energy/area trade-off.

The thesis will be supervised by Professor Benoît Miramond (University Côte d’Azur, LEAT, Sophia Antipolis) and co-supervised by François Duhem (CEA/Spintec, Grenoble).

Applicants should have background in RTL development, system architecture, electronics and programming language such as C/C++ (SystemC appreciated).

MRAM-based synchronous integrated circuit design on advanced technology node for space applications

SL-DRF-18-0178

Research field : Electronics and microelectronics - Optoelectronics
Location :

Spintronique et technologie des composants (SPINTEC)

Laboratoire Spintec (SPINTEC)

Grenoble

Contact :

Gregory DI PENDINA

Lionel TORRES

Starting date : 01-10-2018

Contact :

Gregory DI PENDINA

CEA - DSM/INAC/SPINTEC/SPINTEC

0438784746

Thesis supervisor :

Lionel TORRES

Université de Montpellier - LIRMM

04 67 41 85 67

Personal web page : http://inac.cea.fr/Pisp/gregory.dipendina/index.html

Laboratory link : http://www.spintec.fr/

Nowadays, there are several methods to design microelectronics circuits adapted to space applications, meeting the radiation hardening constraints, using specific techniques or fabrication processes. After a

3 year strong and rich experience in the framework of a Ph. D. in collaboration with CNES, LIRMM and CEA/Spintec, from 2014 to 2017, we would like to expand and reinforce this work. We want to propose novel design architectures embedding emerging non volatile technologies, such as spintronics using MRAM (magnetic memories), for harsh environment, especially for space. Several study have already been done or are currently ongoing on MRAM memories. However, we propose here to integrate MTJ (magnetic Tunnel Junctions), basic element of MRAM, into the computational logic. These MTJs can be used in sequential parts such as flip-flop and latches, or into cells such as NAND, NOR, etc. The final aim is to propose an hybrid CMOS/MRAM logic to harden integrated circuits against space environment. This subject addresses computational digital circuits such as microprocessors for instance. Moreover, STT-MRAM (Spin Transfer Torque) which is the most advanced MRAM technology which start to be commercialized will be used for this work.

On the other hand, the SOT-MRAM (Spin Orbit Torque) technology which is the most emerging MRAM one will also be considered in order to provide the most complete study and the most efficient solution. This work is very prospective and will use very advanced CMOS process. The goal is to fabricate a complete demonstrator and to perform functional and radiation tests with the CNES to validate the robustness of such an approach CMOS/MRAM against particle strikes. This Ph. D. would be mainly co-supervised by the Spintronics IC design team at CEA/Spintec Grenoble and supervised by LIRMM - Montpellier.

Miniature and ultra-sensitive magnetometer for space missions

SL-DRF-18-0141

Research field : Solid state physics, surfaces and interfaces
Location :

Spintronique et technologie des composants (SPINTEC)

Laboratoire Spintec (SPINTEC)

Grenoble

Contact :

Hélène BEA

Claire BARADUC

Starting date : 01-10-2018

Contact :

Hélène BEA

UGA - DRF/INAC/SPINTEC/SPINTEC

04 38 78 08 46

Thesis supervisor :

Claire BARADUC

CEA - DRF/INAC/SPINTEC/SPINTEC

04 38 78 42 35

Laboratory link : http://www.spintec.fr/research/magnetic-sensors/

The aim is to develop a miniature and ultra-sensitive magnetometer (100 fT / Hz^1/2), using magnetic tunnel junctions and microfabrication techniques from microelectronics. This magnetometer could replace the magnetometers currently used on space missions with a mass reduction by a factor of 100. This extreme lightness (~ 1 g without electronics) would represent a competitive advantage over inductive sensors currently used in space missions (mass > 1 kg).

The proposed magnetometer combines a magnetic tunnel junction as sensing element of the sensor, a flux concentrator to amplify the field to be measured, and a magnetic field modulation system to reduce the noise of the measurement. Preliminary studies have shown the feasibility of the basic bricks of this sensor. It is now necessary to optimize the flux concentrator and the magnetic tunnel junction, in particular by developing an innovative junction that is currently the subject of a patent application.

The thesis work will mainly be experimental (microfabrication, electrical and magnetic characterization, noise measurements, magnetic imaging) but will also include analysis and micromagnetic simulations.

Antiferromagnetic spintronics

SL-DRF-18-0274

Research field : Solid state physics, surfaces and interfaces
Location :

Spintronique et technologie des composants (SPINTEC)

Laboratoire Spintec (SPINTEC)

Grenoble

Contact :

Vincent BALTZ

Starting date : 01-10-2018

Contact :

Vincent BALTZ

CNRS - DFR/INAC/SPINTEC/SPINTEC

04 38 78 03 24

Thesis supervisor :

Vincent BALTZ

CNRS - DFR/INAC/SPINTEC/SPINTEC

04 38 78 03 24

Laboratory link : http://www.spintec.fr/research/antiferromagnetic-spintronics/

More : https://arxiv.org/ftp/arxiv/papers/1606/1606.04284.pdf

Antiferromagnetic materials (antiparallel alignment of the atomic magnetic moments) could represent the future of spintronic applications thanks to the numerous interesting features they combine: they are robust against perturbation due to magnetic fields, produce no stray fields, display ultrafast dynamics and are capable of generating large magneto-transport effects. Intense research efforts are being invested in unraveling spin-dependent transport properties in antiferromagnetic materials. Whether spin-dependent transport can be used to drive the antiferromagnetic order and how subsequent variations can be detected are some of the thrilling challenges to address.

The nature of the elements constituting the antiferromagnetic material and the quality of the interfaces will be the adjustable parameters. We will consider mainly the efficiency of spin injection and the interfacial filtering, the absorption of spins in the core of the material and the absorption characteristics lengths, the order temperatures and the magnetic susceptibility, and the efficiency of the spin-orbit coupling via the spin Hall effect.

This PhD thesis work is experimental. It will build on the many techniques of fabrication (sputtering, molecular beam epitaxy, clean room nanofabrication) and characterization (magnetometry, ferromagnetic resonance, transport) at SPINTEC and benefit from the collaboration with our partner laboratories for experiments with a resonant cavity and for access to complementary materials.

Study of physical properties of magnetic skyrmions for sensing applications

SL-DRF-18-0215

Research field : Solid state physics, surfaces and interfaces
Location :

Spintronique et technologie des composants (SPINTEC)

Laboratoire Spintec (SPINTEC)

Grenoble

Contact :

Claire BARADUC

Hélène BEA

Starting date : 01-09-2018

Contact :

Claire BARADUC

CEA - DRF/INAC/SPINTEC/SPINTEC

04 38 78 42 35

Thesis supervisor :

Hélène BEA

UGA - DRF/INAC/SPINTEC/SPINTEC

04 38 78 08 46

Laboratory link : http://www.spintec.fr/research/magnetic-sensors/

Skyrmions are chiral magnetic bubbles: magnetization follows a cycloid along a line across the skyrmion. They can appear in heavy metal/ferromagnet/oxide ultrathin trilayers. Such texture results from the presence of an interfacial interaction called Dzyaloskinskii-Moriya interaction. It makes the skyrmions stable, less sensitive to defects as compared to usual domain walls and easily moveable by electrical current. They are currently very popular as they could be used as dense storage nanoscale data bits, or for magnetic logic.

Their size may be modified by a magnetic field. Moreover, using magneto-optical microscopy, we have recently shown that a gate voltage can modulate the size and density of magnetic skyrmions in ultrathin films, ultimately leading to the realization of a skyrmion switch [1]. This new degree of freedom may thus allow to create multifunctional spintronic devices or to better control the skyrmion properties.



In order to develop skyrmion based spintronic devices, the objectives of this thesis would be:

-to better understand and control the different contributions in the Dzyaloshinskii-Moriya interaction by playing on the materials thanks to a support from theoreticians at Spintec.

- to optimize the tunability of skyrmion properties with the gate voltage by performing a material study. Skyrmion behavior with temperature will also be studied as a device should operate in the -40 to 100°C range for applications.

-to characterize the electrical signature of skyrmions by using magneto-optical microscopy coupled with magnetotransport. This electrical signal is necessary to read the state of a skyrmion-based device but is still a technological challenge, the signals being usually quite small.

- finally, to assess the potential for skyrmions to be used in spintronic devices.



[1] M. Schott et al. Nano Lett., 17, 3006 (2017)

Manipulation of spin currents and magnetic state at the nanoscale using the spin orbit coupling

SL-DRF-18-0058

Research field : Solid state physics, surfaces and interfaces
Location :

Spintronique et technologie des composants (SPINTEC)

Laboratoire Spintec (SPINTEC)

Grenoble

Contact :

Laurent VILA

Jean Philippe ATTANE

Starting date : 01-10-2018

Contact :

Laurent VILA

CEA - DSM/INAC/SP2M/NM

0438780355

Thesis supervisor :

Jean Philippe ATTANE

Universite Joseph Fourier - INAC/SP2M

0438784326

Personal web page : http://inac.cea.fr/Pisp/laurent.vila/

Laboratory link : http://www.spintec.fr/research/spin-orbitronics/

The development of spin electronics, or spintronics, allows to imagine many devices taking advantage of an electronics no longer based solely on the electrical charge of the carriers but also on their spin. This new degree of freedom offers additional means of conveying information, and introduces new ways to manipulating it.

Very recently, a collection of Spin Orbit based spin- to-charge interconversion mechanisms (Spin Hall effects, Rashba and Topological Insulators) were observed experimentally. It appears in the set of non-magnetic metals, semiconductors or oxydes, and sorts the carriers according to their spin state. It allows injecting and detecting spins without necessarily using magnetic materials or a magnetic field, which is both conceptually and technologically very interesting.

In this framework, we wish to create lateral nanostructures taking advantage of pure spin current generated by harnessing the Spin Orbit coupling for both spin to charge interconversion mechanisms and the manipulation of magnetization state of nano-object (dot or magnetic domain wall) by absorption of this current and spin transfer torque. Material of interest will be metals, oxydes and topological insulators to generate or detect spin currents, and will be applied to the manipulation of the magnetic state of a nanoelement, an example of a recent realization being given on the figure.

If subjects related to the spin transfer by absorption of a pure spin current are very competitive, they are scientifically rich, and currently booming. This area of research is still largely open to exploration, and we are benefiting from our recent development of efficient injection and detection devices.

The proposed topic lies in basic research but with a clear opening towards applied research. The trainee will benefit from the technical and scientific environment of the laboratory, and the collaborations put in place with the major actors of the field at the international level. This project is supported by funding from the ANR.

 

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